1. Field of the Invention
The present invention relates to a cartridge detachably attachable to a main body of an image forming apparatus.
The image forming apparatus may be, for example, of a type in which an image is formed on a recording medium by using an electrophotographic image forming process, such as an electrophotographic copying machine, an electrophotographic printer (for example, an LED printer, a laser beam printer or the like) and an electrophotographic facsimile apparatus, and, as an example of the cartridge, there is a cartridge integrally incorporating at least developing means and an electrophotographic photosensitive member as an image bearing member into a cartridge unit which can detachably be mounted to the main body of the image forming apparatus. As another example of the cartridge, there is a cartridge which does not have an electrophotographic photosensitive member and has a developing device integrally including a developer containing container storing developer (referred to as xe2x80x9ctonerxe2x80x9d hereinafter) and which can detachably be mounted to the main body of the image forming apparatus.
2. Related Background Art
In conventional image forming apparatuses using an electrophotographic image forming process, a process cartridge system in which an electrophotographic photosensitive member and process means acting on the electrophotographic photosensitive member are integrally incorporated into a cartridge unit which can detachably be mounted to a main body of the image forming apparatus has been used. According to such a process cartridge system, since the maintenance of the apparatus can be performed by the operator himself without any expert, the operability can be enhanced considerably. Thus, such a process cartridge system has widely been used in the image forming apparatuses.
In such a process cartridge, a photosensitive drum is provided and developing means is used for applying developer (toner) to a latent image formed on the photosensitive drum. The developing means is constituted by joining a developing frame holding a developing roller for feeding out the toner to the photosensitive drum to a toner frame (toner container) containing the toner. Before usage, an opening portion defined in a joined portion between the toner frame and the developing frame is sealingly closed by a seal member. There has been proposed a process cartridge having an automatic seal unsealing device in which, upon first usage, when the process, cartridge is mounted to the main body of the image forming apparatus, the seal member sealing the opening portion of the toner frame is automatically unsealed, and an image forming apparatus capable of driving an automatic seal wind-up device of a process cartridge. Similarly, regarding a developing cartridge and a toner cartridge, there has been proposed an automatic seal wind-up device.
The developing apparatus includes various rotary members and a developing process is effected by rotating such rotary members. As an example, there are a toner supplying roller disposed within a toner container and adapted to supply the toner to a developing roller, carrying and agitating means (referred to as merely as xe2x80x9cagitating meansxe2x80x9d hereinafter) for carrying the toner to the developing frame, and a developing roller.
When the process cartridge is inserted into a predetermined position within the main body of the image forming apparatus, a developing roller input gear coaxial with the developing roller is engaged by a driving gear of the main body of the image forming apparatus, with the result that the developing roller is rotated, thereby rotating various rotary members relating to the developing process.
Nowadays, many process cartridges available on the market have mainly been designed so that various rotary members in the developing portion and cleaning portion, and the photosensitive drum are rotated by a process-cartridge driving gear of a driving device of the main body of the apparatus.
There is one (or two at the maximum) interface between the driving apparatus of the main body and a driven portion of the process cartridge. When two interfaces are provided, one of the interfaces relates to input of the photosensitive drum and the other relates to input of developing relating rotary portions. In this arrangement, image quality can be enhanced, and, by separating the input of the photosensitive drum from the input of developing relating rotary portions, uneven rotation of the photosensitive drum due to a change of load in development is prevented. This arrangement is adopted particularly by a high class machine in which a high quality image is requested. If there are three or more driving input portions for the process cartridge, the cost of the process cartridge is increased, and the positioning between the driving input portions of the process cartridge and the driving portion of the main body of the image forming apparatus becomes complicated, and such techniques are not yet used in the present machines available on the market. Normally, the single input of developing relating rotary portions is used.
Further, in recent years, there has also been proposed a process cartridge in which the toner seal is automatically wound up by a winding shaft, and a technique in which various rotary members, such as the winding shaft, the agitating means, the developer supplying roller and the like are rotated simultaneously by a driving force inputted to the developing portion, has also been proposed.
When there are various rotating means, driving mechanisms for rotating the winding shaft and other rotary members are concentrated at one side in a longitudinal direction of the developing roller. As a result, it is considered that the side at which the driving mechanisms are located extremely protrudes with respect to the developing roller, with the result that an installation space for the driving mechanism in the main body of the image forming apparatus is pressed to bring an unbalanced arrangement of the driving mechanisms. Particularly, since the winding shaft must wind up all the seal automatically, it requires sufficient strength, and, a diameter of the shaft is considered to be normally about 10 mm. In such a case, even when the winding shaft is installed in the driving portion of the process cartridge, the longitudinal dimension (perpendicular to a sheet conveying direction) of the process cartridge including the driving apparatus is lengthened. Further, when the other rotary members such as the toner agitating means and the toner supplying roller are also installed in this driving portion, the driving portion of the process cartridge becomes bulky.
Normally, left and right side plates of the main body of the apparatus are adequately spaced apart from each other not to interfere with the insertion of the process cartridge into the main body of the image forming apparatus. In this case, when the process cartridge in which the driving mechanisms are installed only at one side is inserted into the main body of the apparatus, the side plate (of the main body) corresponding to the driving side must be retarded not to interfere with the insertion of the process cartridge. However, on the side plates of the main body, there are installed not only the process cartridge, but also various units, such as the fixing device, a laser scanner, a sheet conveying portion (from the transfer portion to the fixing device), a sheet feeding portion and the like. Other units than the process cartridge are designed not to have a protruded portion at one side, unlike the process cartridge having the seal winding mechanism in the driving portion, and, in such a case, the side plates of the main body must be designed in consideration of the installation position of the process cartridge within the main body of the image forming apparatus and the configuration of the process cartridge passing through the main body of the image forming apparatus.
For these reasons, when the process cartridge has the construction in which the driving portion extremely protrudes in comparison with the other units, the entire distance between the side plates of the main body must be widened in accordance with the dimension of the process cartridge, or a portion of the side plate associated with the process cartridge must be retarded, i.e., the side plate must be partially recessed.
Normally, at the side of the developing apparatus where the driving mechanisms are located, a driving mechanism of the main body of the image forming apparatus (i.e., driving mechanism of the main body of the image forming apparatus for applying the driving force to the developing apparatus and for transmitting a rotational force from a motor to a developing member) is also installed.
In this way, if the driving mechanisms of the developing apparatus are concentrated at one side with respect to the center of the developing roller, not only the side plate of the main body must be reformed, but also the driving apparatus of the main body of the image forming apparatus must be designed in accordance with the reformed side plate. Since the driving mechanism drives not only the process cartridge but also other units such as the fixing device and the sheet feeding device, if drive input positions of these units are differentiated, the driving mechanism of the main body will becomes complicated (to cope with these units) and expensive.
Further, the reformed side plate influences not only the driving mechanism of the main body, but also an outer cover of the main body of the image forming apparatus for enclosing the driving mechanism. If the outer cover is partially protruded to conceal the protruded portion, the entire system will become bulky.
Further, within the process cartridge, if the driving mechanisms are concentrated at one side with respect to the center of the developing roller, various driving paths such as a driving path to the winding shaft, a driving path to the agitating means and a driving path to the toner supplying roller are partially overlapped with each other, which leads to a complicated arrangement in which gears are multi-overlapped. Thus, if a malfunction occurs once, disassembling and repair of the system becomes difficult. Therefore, it is considered that divisional installation of the driving mechanisms is inevitable.
When the toner seal is not yet unsealed by the winding shaft, the toner seal is bonded to the toner container by ultrasonic welding and the toner seal is also secured to the winding shaft. In this way, in the toner-seal unsealed condition, except for the mechanism for driving the winding shaft, other mechanisms disposed at that side cannot be exchanged.
As mentioned above, if the layers of various driving paths (ranges where the driving paths defined by the gears exist) are installed at one side in an overlapped fashion, the following disadvantages occur:
1. Only a portion of the side plate associated with the process cartridge is protruded, thereby affecting an influence of the installation of the driving apparatus of the main body.
2. The configuration of the side plates of the main body must be changed, and the outer cover is also protruded in accordance with the driving apparatus.
3. Since various driving gears are concentrated in the driving portion of the process cartridge, the disassembling becomes difficult, thereby making exchange of parts in the driving portion difficult.
An object of the present invention is to provide a cartridge in which a toner-seal member can automatically be unsealed.
Another object of the present invention is to provide a cartridge in which drive transmitting portions of the cartridge are prevented from being concentrated at one end in a longitudinal direction of the cartridge.
A further object of the present invention is to provide a cartridge in which an uneven protruded portion is prevented from being created at one end in a longitudinal direction of the cartridge.
A still further object of the present invention is to provide a cartridge in which an outer cover of a main body of an image forming apparatus is prevented from creating an uneven protruded portion and from being made bulky.
A further object of the present invention is to provide a cartridge in which maintenance of a driving system of the cartridge can easily be performed.